Vapor deposition means for strip-coating continuously moving, helically wound ribbon



Sept. 13, 1966 A LORENZ ETAL 3,272,175

VAPOR DEPOSITION MEANS FOR STRIP-COATING CONTINUOUSLY MOVING, HELICALLYWOUND RIBBON Flled May 12, 1965 2 Sheets-Sheet l FIG.1 3'

" FIG. 2

I 42/ I I:

l lLU INVENTORS. F'G. 3 b ALBERT LORENZ PAUL MULLER WALTER REICHELT 52RICHARD SEIZ BERNARD Rossrvsrocx A\\\ WIIIIIIIIIIIIIIA ATTORNEYS Sept.13, 1966 A. LORENZ ETAL 3,272,175

VAPOR DEPOSITION MEANS FOR STRIP-COATING GONTINUOUSLY MOVING, HELICALLYwoum) RIBBON Flled y 1 1965 2 Sheets-Sheet 2 INVENTORS.

ALBERT LORENZ PAUL MULLER WALTER RElcHELT RICHARD SEIZ BERNARDRosErvsTocK ATTORNEYS United States Patent "ice VAPOR DEPOSITION MEANSFOR STRIP-COAT- ING CONTINUOUSLY MOVING, HELICALLY WOUND RIBBON AlbertLorenz, Hanan am Main, Paul Miller, Hanau- Kesselstadt, Walter Reicheltand Bernhard Rosenstock, Hanan am Main, and Richard Seiz, Bruchkobel,Germany, assignors to W. C. Heraeus Gesellschaft mit beschrankterHaftung, Hanan am Main, Germany, a corporation of Germany Filed May 12,1965, Ser. No. 457,249 4 Claims. (Cl. 11849) This invention refers toapparatus for partially coating metallic ribbons under vaucuum byevaporation of the coating material comprising a noble metal, such as,silver.

In earlier times electrical contacts have been made entirely of noblemetals, especially with silver. But in later times they have beenstamped from metal ribbon which were covered with silver only at thearea or strip serving as the contact surface when the contact spring hasbeen formed. Usually only one flat side of the ribbon is coated and onlya part, e.g. a half of this side. But the invention is not restricted tometallic coatings of metallic ribbons. It can also be used for coatingwith other materials.

An object of this invention is to provide an improved manufacture ofsuch partially coated metallic ribbons.

More specifically, it is an object of this invention to provide an easycoating of ribbons of a substantial length.

It is another object of this invention to coat metallic ribbons ofdefinite length, e.g. about 200 m.

Another object of this invention is the partial coating of metallicribbons of indefinite length which are coated by a continuous coatingprocess.

More specifically, an object of this invention is to improve the coatingof ribbons of substantial length under vacuum.

Processes for vacuum coating of long metallic ribbons are known in theart. Also are known, processes for the partial coating of such ribbons.In these processes masking ribbons are used, which cover that part ofthe ribbon which shall remain free from the coating. The masking ribbonmoves with the same speed as the ribbon to be coated and usually is incontact with this ribbon during the coating process itself. However,this has a number of disadvantages.

The masking ribbon must be moved with exactly the same speed as themetallic ribbon to be coated. This can only be fulfilled accurately bycontrolling the speed of both ribbons for which a complicated controllermust be provided. Moreover, the openings or the masking edges of themasking ribbon are coated every time they are in use' So the openings orthe masking edges gradually change their shape and also theconfiguration of the coated surface of the metallic ribbon.

It is an object of this invention to avoid such masking ribbon and stillobtain the desired effect of partially coating.

The invention consists in winding the metallic ribbon to be coated on acylinder, whereby the turns cover one another partially. At aninvariable length of e.g. 100 or 200 m., the whole length of the ribbonis wound on a cylinder of suitable dimensions. The cylinder with theribbon thereon, will be inserted into a vacuum chamber and coated in theusual manner by evaporating the coating material and condensing it onthe free surface of the ribbon. A substantially greater length is woundin the same manner on the cylinder, but it is fed continuously byunrolling from a spool and after the coating process, it is rolled uponanother spool which is advantageously driven by an electric motor.

3,272,175 Patented Sept. 13, 1966 For a better understanding of theinvention together with further objects thereof, reference is made tothe following descriptions, taken in connection with the accompanyingdrawings showing preferred embodiments thereof.

In the drawings:

FIGURE 1 is a cross-sectional view of a coating device forming anembodiment of this invention;

FIGURE 2 shows, partially in cross-section, the most essential part, thecylinder with the metallic ribbon wound on it;

FIGURES 3a and 3b show a ribbon partially coated according to theinvention;

FIGURE 4 is a cross-sectional view of another embodiment of thisinvention;

FIGURE 5 shows a cross-sectional view through the cylinder of FIGURE 4;and

FIGURES 6 and 7 show other cross-sectional views of this cylinder.

The drawings are schematic ones in which all details of no importancefor the understanding of the invention are omitted. The coating devicesare shown especially without constructional parts for holding thedifferent details and without pump sets for generating the necessaryvacuum. Such constructional parts and pump sets suitable for thementioned purposes are known in the art and need no explanation herein.

FIGURE 1 shows a vacuum chamber A with the cylindrical central parthaving flanges 2 and 3 on both ends. It is closed by the covers 4 and 5which also are furnished with flanges 2' and 3. The flanges 2, 2' and 3,3, respectively, are pressed together and sealed by the gaskets 2" and3". The covers are movable and are supported by a construction not shownwhich can be moved in the direction of the axis of the cylinder 1 onrails, not shown.

The cylinder 1 is furnished with a sight glass 6 for observing thecoating process. At the lower side of the cylinder there is provided apipe 7 with a flange connection 8 to the vacuum line 9. This line 9forms the connection to a vacuum pump set, not shown which exhausts thevolume of the vacuum chamber A in the direction of the arrow 10. Thispump set in the usual manner is furnished with vacuum gauges, vacuumcontrollers, floating valves etc. The apparatus is grounded byconnection 77.

To the cover 4 at the right hand side of the drawing is fixed the motorhousing 15 containing reduction gearing. The motor drives the shaft 16extending into the vacuum chamber A and is sealed hermetically in cover4. Said shaft 16 ends in the electrically isolating part 17 which formspart of the end wall 18 of the cylinder drum 19. On this cylinder 19 themetallic ribbon to be coated is wound in a manner which will behereinafter described in connection with FIGURE 2.

To cover 5 on the left hand side of the drawing is fixed a tubularmember 20 extending into the vacuum chamber A. This tube member 20supports the electric heating elements 21. The heating energy is fed bymeans of electric wire connections 22.

In the lower part of the vacuum chamber A are mounted evaporators 25 forthe material with which the ribbon is to be coated. Here can be usedevaporators of any kind known in the art. Suitable are coats of highmelting metals like tungsten or rods of graphite etc. If a layer of asubstantial thickness is desired, it is advantageous to feed thematerial to be evaporated into the evaporators 25 during the coatingprocess. This is also known in the art and needs no further description.

The evaporators 25 shown in FIGURE 1 contain the material 25 to beevapoarte-d. They are heated by an electric current which is fed byelectric wires 26 and the wire connections 27. The wires 26 are'fed intothe vac-' uum chamber A through the hermetic seals 28.

The coating material usually gives off many gases during its firstheating, and in the first moments of the process evaporates undesiredcontaminations contained in it. To prevent the contaminants fromaffecting the coating process, a screen 30 is provided which canmechanically be moved in and out of the direct path from the evaporatorsand the cylinder 19. It screens the ribbon from the condensation ofundesired material if it is moved in. Screen is supported by movable arm31 led into the vacuum chamber A through seal 32.

It is known in the art to clean the surfaces to be later coated by aglow discharge in the first time of evacuation. For this purpose anelectric connection 35 is provided which is led through seal 36. Thisconnection has a contact 37 sliding on the metallic end wall 18 of thecylinder 19. The connection 35 and the sliding contact 37 can beconnected to a high voltage generator, not shown.

FIGURE 2 shows the cylinder drum 19 on which has been wound a length ofmetallic ribbon 40 to be metallized or coated. The first winding 41 hasbeen applied to the left side of the cylinder 19. The next winding 42partially covers the first winding. Also the following windings areapplied in such a manner so that they cover a part, e.g. the half width,of every preceding winding. The last winding 43 is held by a simpleclamping device, 44.

For producing metallic coatings according to the process given by theinvention, the apparatus described in connection with FIGURES 1 and 2 isutilized in the following manner.

The cover 4 is removed from the middle part 1 to such a distance thatthe cylinder is outside of part 1. Then the metallic ribbon whichearlier had been cleaned is wound on the cylinder 19 according to FIGURE2 and the cover 4 is brought back to the position shown in FIG- URE 1for hermetically closing the vacuum chamber A. The pump set is switchedon and the vacuum chamber evacuated to the desired degree of vacuum.After this the high voltage generator is connected with the connectionend 35 thereby generating a glow discharge between the cylinder 19 orthe surface of the metallic ribbon wound on it and the other metallicparts grounded by the connection 11. This glow discharge cleans thesurface of the ribbon to be coated from all vapors which may becondensed on it and facilitates the coating;

After this cleaning process, the heating current to the evaporators 25is switched on. They reach a temperature sufficient for the evaporationof the material 25' after a limited time, e.g. 5 minutes. After anadditional time, egg. 2 minutes, the screen 30 is moved out, and thecoating of the ribbon 40 wound onto the cylinder 19 begins. During thecoating process, the cylinder 19 rotates for equally coating of theentire free surface of the ribbon 40.

After a coating of desired thickness has been produced, the heatingcurrent to the evaporators is switched off and/ or the screen 30 movedin, the vacuum is compensated by llooding the vacuum chamber and thecover 4 removed for unrolling the coated ribbon.

FIGURE 3 shows the metallic ribbon in view (FIG- URE 3a) andcross-section (FIGURE 3b). The ribbon is partially coated by the layer51. During the coating process the other part 52 of the ribbon wascovered by the next winding according to the FIGURE 2.

The embodiment of the invention shown in the FIG- URES 1 and 2 issuitable for the coating of limited lengths of the metallic ribbon. On acylinder 19 with a middle diameter, d, of approximately cm. and alength, l, of also about 100 cm. can be wound a ribbon length of 100 m.,if the width of the coated part 51 FIGURE 3 is about 3 cm. Otherdimensions of the cylinder and of the coated width will allow to coateven greater lengths.

The cylinder 19 shown in the FIGURES 1 and 2 has been drafted somewhatconically. This is especially advantageous as by this the surface to becoated is parallel to the axis of the cylinder 19 and can be coatedequally by several evaporators 25, each of which has the same distancefrom its axis. The angle of the conus depends on the thickness of theribbon and on the width of the coated part or stripe 51, FIGURE 3.

The FIGURES 4 to 7 show another embodiment of the invention, it is to benoted that same parts are indicated by same numbers.

The main difference between the embodiment already described .and thisembodiment consists in the feature that the apparatus according toFIGURES 1 and 2 is designed for coating limited lengths up to e.g. 200m. while the embodiment shown in the FIGURES 4 to 7 is capable ofcoating practically unlimited lengths of ribbons. The invention isapplied to a continuous coating process as the ribbon is also wound ontoa cylinder and one winding covers the next winding partially.

In FIGURE 4, a bar 101 is fixed to cover 4. This bar supports thecylinder 102 in the same manner as in FIG- URE 1, but the bar 101 andthe cylinder 102 do not rotate. Onto the periphery of the cylinder, themetallic ribbon 103 is wound which is unrolled from spool 104 and afterthe coating process rolled upon the spool i105 driven by the motor 106.Spools 104 and 105 are also supported by the bar 101 so that they can bemoved together with the cylinder 102 and the cover 4. The windings ofthe ribbon 103 cover one another partially as shown in FIGURE 2. Theribbon 103 slides on the cylinder 102 during the coating of its entirelength.

FIGURE 5 shows how the coated ribbon is advan' tageously taken from thecylinder 102 to the spool 105. Near the periphery of the cylinder 102, aroller 106 is mounted in a slit in the cylinder. In the interior ofcylinder 102, another roller 107 is so arranged that its axis forms anangle with the axis of the cylinder 102. Thus the ribbon 103 leaves theopen end of the cylinder, eventually through an end slit providedtherefore, in the direction to the spool 105 also disposed at an angleto the axis of cylinder 102.

Usually the ribbon 103 during the coating process can slide on thesurface of the cylinder 102. If this is undesired or harmful or if theforce for the transport of the ribbon seems to be too great, cylinder102 can be furnished with rollers. Two perpendicular crosssections ofsuch an arrangement are shown in the FIG- URES 6 and 7.

The shell 110 of cylinder or as shown in FIGURES 6 and 7, has spiralgrooves 111 in which rollers 112 are inserted. Each of the spiral rolls113 between the grooves 111 serves as a guide for one winding of theribbon 103 as shown in FIGURE 6. The rollers 112 have different andgradually decreasing distances from the axis of the cylinder wall 110.The ribbon 103 forms a spiral, the diameter of which decreased to theleft side of FIGURE 6. Thus the windings cover one another and can movewithout any sliding one on the other.

The coating process is performed in the same manner as above alreadydescribed.

Cover 4 is removed from the middle part 1 and with this cover the bar101 and the cylinder 102 and the holding devices for the spools 104 and105, fixed and supported by bar 101. A spool 104 filled with themetallic ribbon is inserted into its holding device and the ribbon iswound around the cylinder 102, thread through the opening for the guideroller 106 in the side of the cylinder 102 and given onto the surface ofthe roller 107. Then the end of the ribbon is fixed on the spool 105.

In the meantime, the material to be condensed on the ribbon has been putinto the evaporator 25. Then the cover 4 is moved and sealed to themiddle part of the chamber. The pump set not shown, connected to thepipe line 9 is switched on and evacuates the vacuum chamber A to thedesired vacuum. The glow discharge is ignited and switched off.Thereafter the vacuum chamber is evacuated to the vacuum necessary forthe coating process. The heating of the evaporator is energised, andafter some time the screen is moved out.

At this moment motor 106 is switched on which transports the ribbon fromthe spool 104 over the periphery of the cylinder 102. During the passageof the ribbon over the cylinder 102, it is partially coated by thematerial evaporated from the evaporator 25 at the lower side of thecylinder 102. The speed is so regulated that a coating is performedhaving the desired thickness.

Then the ribbon is rolled upon the spool 105. After exhausting theribbon on the spool 104, the heating of the evaporator and the pump setare switched off, the evacuated space flooded to atmospheric pressureand the cover 4 removed. The coated ribbon with spool 105 are then takenfrom its holding device and a new ribbon may be inserted for a newcoating process.

The heating device 21 provided in the apparatus shown in the FIGURES 1,4 and 5 serves for heating the ribbon during the coating process. Thisimproves the durability of the coated layer.

The coating process described works very well. Pre ferably, it is usedfor the coating of electric contact springs made of different sorts ofbrass, especially of a beryllium alloy. Such brass ribbons were coatedwith silver or other noble metals to different, desired thicknesses.Thin coatings are suitable for electric contacts which are switched onlyseveral times. Examples are the contacts of apparatus parts insertedinto a frame from which they are removed only for repair purposes.

According to the invention, not only thin coatings were performed, thethickness of which is only several an (1/ 1000 mm.) but alsosubstantially thicker layers up to 0.2-0.3 mm. were manufactured whichserve as contacts for switches and controllers working many times everyminute.

It is to be noted that the invention is not restricted to the metalliccoatings described. It can be used also in the case of dielectriccoatings applied to a part of surface of metallic ribbons. Suchisolating layers can be useful in assembling electrical parts in a smallvolume.

Having thus described the invention, the following is claimed:

1. An apparatus for partially coating a flat elongated metallic ribboncomprising, in combination:

(a) a sealable chamber;

(b) means for evacuating said chamber;

(c) evaporator means in said chamber;

((1) a drum in said chamber spaced from said evaporator means, said drumhaving an axis and a conically tapering face about said axis;

(e) two reel means rotatably mounted in said chamber;

(f) a motor means for rotating one of said reel means;

and

(g) securing means for securing an elongated ribbon on said face in aplurality of axially consecutive turns in such a manner that eachportion of said ribbon is parallel to said axis, and an edge portion ofone turn overlaps an edge portion of an axially adjacent turn while theother edge portion of said one turn is overlapped by an edge portion ofanother axially adjacent turn, said securing means including a guidepulley for guiding a ribbon from the other one of said reel means oversaid face in said turns while respective portions of said ribbon arewound on said one reel means and said ribbon is moved longitudinallyunder the force of said motor means.

2. An apanatus as set forth in claim 1, further comprising means formoving said ribbon in the direction of elongation thereof over said facein said turns, said drum being secured against rotation about said axis.

3. An apparatus as set forth in claim 2, a plurality of support membersmounted on said drum, respective portions of said support membersjointly constituting a portion of said face, each of said supportmembers being rotatable about an axis substantially parallel to the axisof said drum.

4. An apparatus as set forth in claim 3, wherein said support membersare arranged in a helical row on said drum.

References Cited by the Examiner Lorenz et al.: German application No.1,131,484, publication 6-14-1962, copy in 118-49, (1 sht. dwg., 2 pp.spec.).

MORRIS KAPLAN, Primary Examiner.

1. AN APPARATUS FOR PARTIALLY COATING A FLAT ELONGATED METALLIC RIBBONCOMPRISING, IN COMBINATION: (A) A SEALABLE CHAMBER; (B) MEANS FOREVACUATING SAID CHAMBER; (C) EVAPORATOR MEANS IN SAID CHAMBER; (D) ADRUM IN SAID CHAMBER SPACED FROM SAID EVAPORATOR MEANS, SAID DRUM HAVINGAN AXIS AND A CONICALLY TAPERING FACE ABOUT SAID AXIS; (E) TWO REELMEANS ROTATABLY MOUNTED IN SAID CHAMBER; (F) A MOTOR MEANS FOR ROTATINGONE OF SAID REEL MEANS; AND (G) SECURING MEANS FOR SECURING AN ELONGATEDRIBBON ON SAID FACE IN A PLURALITY OF AXIALLY CONSECUTIVE TURNS IN SUCHA MANNER THAT EACH PORTION OF SAID RIBBON IS PARALLEL TO SAID AXIS, ANDAN EDGE PORTION OF ONE TURN OVERLAPS AN EDGE PORTION OF AN AXISLLYADJACENT TURN WHILE THE OTHER EDGE PORTION OF SAID ONE TURN ISOVERLAPPED BY AN EDGE PORTION OF ANOTHER AXIALLY ADJACENT TURN, SAIDSECURING MEANS INCLUDING A GUIDE PULLEY FOR GUIDING A RIBBON FROM THEOTHER ONE OF SAID REEL MEANS OVER SAID FACE IN SAID TURNS WHILERESPECTIVE PORTIONS OF SAID RIBBON ARE WOUND ON SAID ONE REEL MEANS ANDSAID RIBBON IS MOVED LONGITUDINALLY UNDER THE FORCE OF SAID MOTOR MEANS.